Saturday, February 11, 2012

I discovered an article [1] this morning that really excites me, because I think it gets at the core problem in most of the chronic diseases of aging, although its focus is on the nervous system. The article is titled, “Na+,K+-ATPase: functions in the nervous system and involvement in neurological disease.” The article maintains, and, happily, I had recently been reaching the same conclusion, that impairment in sodium-potassium ATPase (Na+,K+-ATPase) is the key early marker of neurological diseases like Parkinson’s and multiple sclerosis.

What is Na+,K+-ATPase and why is it important? This protein is called an “integral membrane protein” because it is tightly integrated in the membrane of the cell. It is crucially present in all cells, and its main job is to make sure that there’s lots of potassium (K+) inside the cell, and that sodium (Na+) is mostly outside the cell. It also has the arduous task of making sure the cell interior is appropriately negatively charged relative to the outside world. It essentially assures that there is a voltage gradient (like a battery) across the cell membrane, with the interior of the cell being the anode. It can do this by operating the pump, because it pumps out three sodium ions for every two potassium ions that it pumps in. Since both potassium and sodium have a charge of +1, the net effect is to charge the battery: push out a +1 charge every time it pulls in two potassiums and ships out three sodiums.

This article claims that cells expend most of their energy operating this pump! Who would have guessed that? Impairment in the pump comes about when the cell runs low on ATP, the energy currency of all life. Every time it runs the pump, it uses up ATP. If the mitochondria (the powerhouses of the cell) can’t keep up with the supply, the cell battery starts losing charge, and then “all hell breaks loose.”

So the article puts the blame squarely on mitochondrial dysfunction. Over time, mitochondria suffer oxidative damage from dangerous reactive molecules like peroxynitrite (ONOO−), which can destroy the iron-sulfur clusters the mitochondria depend upon for electron transport. However, I believe an earlier problem, preceding mitochondrial damage, is at play. The problem is that the cell is suffering from an excessively leaky cell membrane – a membrane that too easily allows sodium ions and potassium ions (which are unfortunately very small) to sneak back across the membrane in the wrong direction, i.e, to “leak.”

Why would the cell membrane be leaky? The answer is easy – an impoverished supply of cholesterol sulfate! Both cholesterol and sulfate play essential roles in maintaining a healthy membrane function. I refer you to an excellent article written by Thomas Haines [2], which points out very clearly that cholesterol, by intermingling with the polyunsaturated fatty acids that form the bulk of the membrane, causes the fatty acids to configure themselves more tightly and more regularly, such that it becomes much more difficult for small ions like sodium and potassium to pass through. When cholesterol is deficient in the membrane (due to the depleted supply of cholesterol sulfate), sodium and potassium can much more easily leak across the membrane.

The other problem is insufficient sulfate, and to better understand this aspect you need to read some of the papers by Gerald Pollack [3, 4], who has made a tremendous contribution in revitalizing interest in questions about the structure of water, which makes up roughly 70% of the human body. So now I need to digress a bit and explain in simple terms the Hofmeister series. Ions – both cations (positive) and anions (negative) can be arranged along a continuous scale according to the Hofmeister series. At one extreme you have the strong kosmotropes (sulfate is an example) which are called “structure making” with respect to water. At the opposite extreme are the chaotropes (potassium is an example) which are “structure breaking.” Kosmotropes and chaotropes can be either negatively or positively charged, and their charge has a different kind of effect on the cell (increasing or decreasing its battery strength), which is also very important. Kosmotropes (structure making) cause the water surrounding them to become almost like a liquid crystal. And, due to the orderly arrangement of the water molecules, they effectively create a shield around them that keeps other ions away.

You can perhaps now see why sulfate would be important to a cell. I have spoken before in this blog about the importance of sulfate in the extracellular matrix proteins of all cells. I have mentioned that sulfate keeps bacteria out because of the repellent property of two negatively charged “particles.” But sulfate can also keep the small ions out, by forming a crystalline structure around itself – something that Pollack refers to as an “exclusion zone.” Interestingly, as an aside, the exclusion zone around a sulfate molecule grows much bigger when the water is exposed to light, especially infrared light (IR). Pollack claims that the exclusion zone grows by a factor of four when a kosmotrope is exposed to IR [3].

So when the supply of cholesterol sulfate to a cell has been inadequate for a long time, the cell begins to find itself in a very difficult state, where there isn’t enough sulfate sprinkled around its walls to maintain a proper exclusion zone, and there isn’t enough cholesterol in its cell membrane to keep the fats from allowing small ions to cross. Now it has to expend much more energy pumping ions, and this leads to a great deal of stress, as it requires the cell to consume much more fuel and oxygen, and excess metabolism is risky business due to all the reactive oxygen species it generates.

Coming back to the Na+,K+-ATPase article, a very enlightening paragraph describes succinctly what happens as the pump begins to fail [1], p. 287:

“The inability to maintain transmembrane Na+,K+ gradients results in collapse of the membrane potential; impaired activity of glutamate transporters; secondary Cl− and water influx, and thus intracellular swelling and accumulation of intracellular Ca+2... This triggers downstream enzymatic cascades leading to injury of the gray and white matter.”

There is a lot packed into the above paragraph, all of which is important. But, clearly, the cell is in trouble! I will have to return to this paragraph in a later blog post about taurine, because the entry of chloride (Cl−) and water into the cell have important consequences to taurine metabolism. But for now I want to focus on the implications of the subsequent calcium entry. And for this we have to return to the discussion on kosmotropes and chaotropes. Calcium is a significantly bigger molecule than either sodium or potassium, and therefore it’s much less prone to leak, which can make it an attractive molecule for maintaining ionic balance. However, it is very different from potassium on the Hofmeister series: instead of being a chaotrope, it is a kosmotrope. This is a huge difference – recall that sulfate is also a kosmotrope, and if the cell continues happily synthesizing sulfate it is going to have too many kosmotropes and not enough chaoptropes on its hands.

As I’ve said before, when calcium enters a cell that contains eNOS, the calcium binds with calmodulin, and this calmodulin-calcium complex then causes eNOS to detach from the cell membrane and start producing nitric oxide (nitrate) instead of sulfate. There’s an enzyme called nNOS (neuronal nitric oxide synthase) in neurons, and it too will start producing nitrate when it sees calcium entering the cell. Why is this? Well, my best guess is because nitrate is a chaotrope, like potassium. Chaotropes and kosmotropes have to be balanced to prevent proteins from either precipitating out (too many kosmotropes) or dissolving (too many chaotropes). Furthermore, I think an individual cell has to make a commitment to producing either potassium sulfate or calcium nitrate as the ionic mix to balance both their electrolytes and their chaotrope/kosmotrope ratio. It can’t be on the fence about this.

There’s a very compelling reason for this: eNOS produces superoxide as a precursor to sulfate and it produces nitric oxide as a precursor to nitrate. So, if some of the eNOS molecules were producing sulfate and others were producing nitrate, there would be a mixture of nitric oxide and superoxide gases simultaneously present in the cell. This is very dangerous, because these two gases react to form peroxynitrite (ONOO−), the highly reactive gas that will destroy the mitochondria’s ability to produce ATP. So we’ve come full circle here! Switching back and forth between nitrate and sulfate synthesis leads to an excess burden of peroxynitrite, which causes mitochondrial damage. Eventually, the cell has no choice but to permanently switch to a calcium-nitrate solution, because there isn’t enough energy to keep on pumping sodium and potassium ions back to where they belong. Cells live under a lot of constraints, and it’s truly remarkable that they perform as well as they do most of the time!

Now I want to turn, once again, to aluminum. Recall that aluminum is an adjuvant that is added to vaccines, and that the aluminum burden our nation’s children are exposed to through vacines has been steadily growing over the past 15 years. Aluminum is a much more potent kosmotrope than calcium, and it binds to calmodulin with an affinity that’s an order of magnitude stronger than that of calcium [5]. So, if even a small amount of aluminum gets into a cell, it will bind to calmodulin, mimicking calcium, and stimulate eNOS to detach from the cell membrane and start making nitrate instead of sulfate. This is very wise, because it turns out that aluminum sulfate is a reagent that is used in chemistry for precipitating out proteins from a cell. You should think about amyloid beta and tau protein plaque at this point: these are proteins that have precipitated out! And their accumulation in the brain is a hallmark of Alzheimer’s disease.

So, in summary, here’s the situation as I see it. The cell suffering from too little cholesterol in its membrane and too little sulfate in its surround is stuck with a huge problem because sodium and potassium are leaking across its membrane at an unacceptably high rate. It has to burn a lot of energy (generate ATP) to keep the pump going to restore the wayward ions. After a point (probably when the ATP starts to run out) it “decides” that the better option is to forget about trying to maintain a high potassium content, and instead use calcium as a cationic buffer. But calcium is a kosmotrope instead of a chaotrope, so the NOS (eNOS or nNOS) has to switch from producing sulfate to producing nitrate, to compensate. When a cell is suddenly confronted with an onrush of aluminum (due to a vaccine), it has no choice but to quickly switch to nitrate production, to avoid a catastrophic precipitation of its proteins. And the really disturbing thing is that aluminum can gain entry more readily when sulfate supply is impoverished in the cell’s extracellular matrix.

As people get older, they often suffer from osteoporosis – the leaching of calcium from the bones. They also tend to build up calcified plaque in the arteries (“hardening of the arteries”) and calcified heart valves. I think this is a direct consequence of insufficient cholesterol sulfate in the artery wall and in the heart. The calcium is leached from the bones in order to supply it to these other cells, which would die if they can’t maintain their charge gradient. They’re willing to turn into bone if that’s what it takes to protect them from a certain death.